Design of symmetric planar fishnet metamaterials for optical wavelength range

In this work we analyze fishnet-type optical metamaterials with full electromagnetic symmetry, fabricated in an ultrathin, freestanding film (self-supported nanomembrane). We utilized the finite element method to simulate the response of various laminar fishnet geometries, including metal-dielectric-metal and dielectric-metal-dielectric-metal-dielectric multilayers. We varied metal and dielectric thickness, nanoaperture radius, metal and dielectric materials. We considered the tunability of the spectral characteristics of the fishnet by bringing a dielectric analyte in contact with its exposed surfaces. Such tunability is of importance for all-optical sensors of chemical or biological analytes, but also for the performance of general fishnet nanoaperture arrays in real operating conditions, where the introduction of the ambient gases and fluids will modify their plasmonic properties.